The present invention relates to field burning apparatus, and more particularly to an apparatus for thermally cultivating a field by continuously advancing fire in the direction of travel of the apparatus after combustible material on the field has been initially ignited.
In certain types of agriculture, it is often desirable to thermally cultivate the land. For instance, after a crop has been harvested, residue such as straw must be removed either through gathering or burning. Machine gathering is time consuming and expensive and the problem still remains with respect to disposing of the gathered residue.
A more effective alternative to gathering is so-called thermal cultivation which involves setting fire to a field. Such thermal cultivation not only burns away combustible residue material, but also kills bacteria, insect pests and fungi. In the production of certain types of grass seeds, harvest must take place in a relatively short time period after which straw residue must be removed. Open field burning has proved effective in cleansing the crop after harvest and rapidly removing excess straw.
Open field burning is generally accomplished by the setting of large fires and controlling the spread of fire by use of water trucks, etc. However, open field fires carry flame and smoke high into the air, thus adding smoke pollution to the atmosphere. With the increased levels of air pollution due to automobiles, industry, etc., open field burning has come under attack as merely adding to the overall levels of unacceptable pollution. As a consequence, legislation has been proposed to eliminate or substantially lessen open field burning. In response to such legislation, various machines have been designed which will contain a fire over a specified field region for producing emissions essentially at ground level. Such machines typically take the form of large and bulky wheeled vehicles which move over the surface of a field and provide a source for igniting and continuously maintaining a fire beneath a covered portion of the machine.
Unfortunately, these machines suffer from a number of significant drawbacks. First of all, the heat built up in such a burning apparatus is quite high, and must be removed along with smoke through a stack. Prior art machines may take the form of large, covered machines having multiple stacks arranged on top of the burning region. These stacks include exhaust fans integrally arranged within the stack to remove products of combustion but because of excessive heat, the fans are subject to destruction.
Another problem present in prior art machines is that the machines are extremely difficult to transport because they are bulky and heavy. Prior art machines are constructed of fixed dimensions and often may not be effectively transported over highways because of their large width and heighth.
Another problem present in prior art machines resides in the fact that burners must be continuously operated in order to maintain a fire within a machine's burning chamber. Furthermore, it has proved difficult to contain a fire within the burning chamber because fire tends to spread out underneath the sides of the burning chamber to other regions of the field.
Prior art machines also suffer from the drawback that complete combustion does not take place at a rearward part of the machine due to excessive smoke build up. Complete combustion of straw may not occur and excessive carbon residue may remain on the field after a machine passes thereover.